How Air Conditioning Work

Monday, January 5, 2009

type of condenser

1. Air-Cooled Condensers
There are two types under this category :
a. Natural Convection.
b. Forced-Air Type.

(a) Natural Convection

Air movement over the surface of condenser tubes is by natural convection. As air comes in contact with the warm-condenser tubes, it absorbs heat from the refrigerant and thus the temperature of the air increases. Warm air being lighter, rises and in its place cooler air from below rises to take away the heat from the condenser. This cycle goes on.

(b) Forced-Air Circulation

This type employs a fan or blower to move air over the condenser coil at a certain velocity. The condenser coil is of the finned type. Fins in such coils are closely spaced (ringing between 8 and 17 fin per inch). The space between the fins get choked with dirt and lint. Therefore to obtain optimum capacity, the fins should be kept clean. To circulate air over the condenser, fans are mounted on the shaft/pulley of the compressor motor. For bigger-capacity plants a separate motor is used to drive the fan or blower. This also applies to the hermetic-compressor units.

2. Water Cooled Condensers

There are three types of condensers which fall under this category: -

(a) Double Tube Condensers

The double tube condenser consists of two tubes so arranged that one is inside the other.Water is piped through the inner tube while the refrigerant flows in the opposite direction in the space between the inner and outer tubes. With this arrangement, some air-cooling of the refrigerant is provided in addition to the water cooling.

(b) Shell-And-Coil Condenser

The shell and coil condenser is made up of one or more bare-tube or finned-tube coils enclosed in a welded steel shell. The condensing water circulates through the coils while the refrigerant is contained in the shell surrounding the coils. Hot refrigerant vapor enters at the top of the shell and condenses as it comes in contact with the water coils. The condensed liquid drains off the coils into the bottom of the shell, which often serves also as the receiver tank. As a general rule, shell and coil condensers are used only for small installations up to approximately 10 tons capacity.

(c) Shell And Tube Condensers

The shell and tube condenser consists of a cylindrical steel shell in which a number of straight tubes are arranged in parallel and held in place at the ends by tube sheets. Construction is almost identical to that of the flooded-type shell and tube liquid chiller. The condensing water is circulated through the tubes, which may be either steel or copper, bare or extended surface. The refrigerant is contained in the steel shell between the tube sheets. Shell and tube condensers are available in capacities ranging from 2 tons up to several hundred tons or more.

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